MORPHOLOGY AND EVOLUTION
abductor hallucis and flexor brevis hallucis. The lateral plantar artery, after giving off the lateral calcanean arterv to the skin of the heel and muscular branches to the
flexor brevis digitorum, accessorius and abductor minimi digiti, divides into superficial and deep divisions. The former supplies the skin of the two outer digits; the latter supplies the interossei and tarso-metatarsal joints, and completes the plantar arch with the arteria dorsalis pedis.
The Apes are characterized by the possession of a well-marked branch of the femoral arterv known as the
arteria saphena. It runs down into the foot where it participates in the formation of an arterial arcade on the dorsum. Eventually it becomes the dorsalis pedis, which combines with the lateral plantar artery to form the plantar arterial arch. In the Chimpanzee the dorsal ^arterial arcade supplies the skin of all the toes except •the hallux. In the Gorilla the arteria saphena gives off a deep plantar artery, and in all the Apes it supplies the tarsal joints.
Section B.—THE VEINS.
The venous system, unlike the arterial, does not exhibit many characters which are very different from those in Man.
Veins of the Head and Neck.
In the Chimpanzee (fig. 45, A.), the anterior facial "vein (A.F.V.) begins by the confluence of palpebral veins from the eyelids and lateral nasal veins. It runs ^downwards and backwards and crosses the mandible •at 'the anterior border of the masseter muscle. It runs between the mandible and subrnaxillary gland.